U.S. patent number 4,190,073 [Application Number 05/727,031] was granted by the patent office on 1980-02-26 for choke for controlling the flow of drilling mud.
Invention is credited to Jack R. Claycomb.
United States Patent |
4,190,073 |
Claycomb |
February 26, 1980 |
Choke for controlling the flow of drilling mud
Abstract
This apparatus disclosed in its preferred form is a choke for
controlling the flow of drilling mud which is highly abrasive. The
abrasive drilling mud is introduced through a lateral port and an
elongate tubular body. In the tubular body, a fluid actuated,
double acting piston is forced to a choke control position. The
piston has appended to it a centralized tubular extension which
receives a sleeve of wear resistant material. The sleeve is
positioned in a circular chamber communicated to the lateral port
where the drilling mud is introduced. It travels toward a seat
downstream of the body. The seat is formed of hardened material.
The downstream outlet of the body is additionally lined with a wear
resistent sleeve.
Inventors: |
Claycomb; Jack R. (Houston,
TX) |
Family
ID: |
24921054 |
Appl.
No.: |
05/727,031 |
Filed: |
September 27, 1976 |
Current U.S.
Class: |
137/238;
137/329.02; 137/329.03; 137/329.04; 166/320; 175/38; 251/324;
251/333; 251/63 |
Current CPC
Class: |
F16K
25/04 (20130101); Y10T 137/4245 (20150401); Y10T
137/6171 (20150401); Y10T 137/6167 (20150401); Y10T
137/6174 (20150401) |
Current International
Class: |
F16K
25/00 (20060101); F16K 25/04 (20060101); F16K
051/00 () |
Field of
Search: |
;137/329,329.01,329.02,329.03,329.04,516.25,489,238 ;166/91,320
;175/38 ;251/35,63,324,210,333 |
References Cited
[Referenced By]
U.S. Patent Documents
Primary Examiner: Schwadron; Martin P.
Assistant Examiner: Walton; G. L.
Attorney, Agent or Firm: Gunn and Lee
Claims
I claim:
1. A choke for controlling the rate of flow of mud comprising:
a hollow housing;
a movable valve element in said housing;
an encircling valve seat in said housing;
contacting surfaces on said valve element and valve seat which
include tapered throttling surfaces which, on separation, define a
controllable throttling passage and which contact one another on
closure wherein said throttling surfaces include:
(a) a tapered surface on said valve seat cooperative with a surface
on said valve element, which, on closing movement of said valve
element relative to said valve seat, defines a flow path between
said valve element and said valve seat which is narrowed
sufficiently to permit flow of mud while preventing entry of
particles above a certain size in the mud;
(b) means for directing the flow from said tapered surface in a
flushing manner across the surface of said valve element;
downstream transverse shoulders on both said valve element and
valve seat which are parallel to one another and which facially
close and contact against one another to close the flow through
said housing, said shoulders being sheltered from fluid flow
through said tapered surfaces by their respective locations on said
valve element and valve seat, said shoulders being relatively
spaced on said valve element and valve seat to close and contact
after said tapered surfaces move to their narrowest spacing
therebetween and wherein said tapered surfaces are concentric of
one another and wherein one of said tapered surfaces connects
immediately to said transverse shoulder.
2. The apparatus of claim 1 including a piston having a protruding
end portion equipped with a detachable means for mounting said
valve therein for axial telescoping movement into and out of
engagement with said valve seat.
3. The apparatus of claim 2 including a cylinder surrounding said
piston and aligning it for sealing movement into and out of contact
with said valve seat.
4. The apparatus of claim 3 including a hollow body having an axial
passage for receiving and supporting said valve seat therein.
5. The apparatus of claim 4 including a port opening into said
hollow body introducing a flow of fluid toward said valve seat, and
a second port downstream from valve seat which serves as an
outlet.
6. The apparatus of claim 4 including an elongate body of circular
cross section which terminates in an end portion serving as said
valve and which body is mounted on said piston, said piston
incorporating a bolt means centered therein which removable clamps
said valve body in place.
7. The apparatus of claim 6 including lock means which clamps said
valve seat into a fixed position relative to said valve seat, said
lock means comprising a latch means for an elongate hollow sleeve
comprising said valve seat.
8. The apparatus of claim 7 wherein said sleeve is double ended and
duplicated at both ends, each end including said valve seat and
being reversable to enable said sleeve to be repositioned and
thereby use both ends.
9. The apparatus of claim 8 wherein said valve is a portion of a
removable part which is provided with duplicate ends and is
reversably received in said choke to enable both ends to function
as a valve element.
Description
BACKGROUND OF THE PROBLEM
In the drilling of an oil well, the drilling lubricant is called
drilling mud. It picks up cuttings from the bottom of the well and
carries them to the top of the well and then to a mud pit where the
chips or cuttings are separated. This permits the mud to be
recycled and used again. The fluid flow system involving the mud is
a high pressure system; accordingly, it is necessary to control
this flow system with a choke. Chokes however, run into great
difficulties in that the mud and the cuttings carried by it are
very abrasive. Because they are abrasive, they rapidly destroy the
valve and seat mechanism in the choke. The patents thus listed
below are representative patents known to represent various and
sundry choke flow mechanisms.
The success or failure of the prior art devices is somewhat
subjective dependent on the goals; nevertheless, the present
apparatus meets a need and provides a solution for that need as is
disclosed hereinafter. The improved relative wear factors and the
related shut down of equipment to replace the choke yields some
evidence of the efficacy of the present apparatus and in particular
point out how this device is able to control the highly abrasive
volume of mud which flows through the mud handling system. It is
very desirable to maintain a regulated back pressure in the system;
accordingly, control of this back pressure through the use of the
present device and in particular the longevity of the device
signify the value thereof.
SUMMARY OF THE DISCLOSURE
The choke of the present device is an elongate tubular housing
having in one end a closure or plug which entraps a fluid operated
piston. The piston is made double acting by applying pressure to
both faces controllably. The piston has a centralized plug appended
to it which receives thereabout a valve member formed of an
extremely hard material. It is located in a circular chamber which
communicates with a lateral port where the mud flow from the well
is introduced. The lateral port is directed at the valve element
which is able to withstand the wear of the flow.
The apparatus further includes a circular valve seat which is
inserted downstream. The valve seat is also made of hardened
material. It has a tapered leading edge. It has an edge which
matches or mates with the valve element itself. As the two are
brought together, they close off the passage through the choke. The
valve seat is a hollow circular ring which communicates with an
outlet passage.
DESCRIPTION OF THE DRAWINGS
The single drawings is a sectional view taken through a diameter of
the choke assembly of the present invention illustrating details of
construction.
DESCRIPTION OF THE PREFERRED EMBODIMENT
The choke of the present invention is identified by the numeral 10
and incorporates an elongate tubular body 12. The body 12 is closed
at one end by a plug 14 which is joined to the body 12 at a set of
threads 16. The plug is provided with a pair of drilled openings 18
to enable it to be grasped by a spanner wrench to be removed. The
plug is axially drilled with a passage 20 which passage is exposed
to the exterior at a threaded opening 22 to enable it to be
connected with a fluid line terminating in an appropriate threaded
fitting. Pressurized fluid at a selected pressurized level is
introduced through the passage 20 and fills a chamber 24. The
chamber 24 is pressurized to a desired level for reasons to be set
forth. The plug defines one end of the chamber 24 and a piston 26
is received therein. The piston has a surrounding seal 28 which
seals against leakage along the piston wall 30. The piston wall 30
terminates at a shoulder 32. The piston as shown is equipped with a
protruding surrounding shoulder or extension 34. The extension 34
in conjunction with the facing shoulder 32 define a circular
chamber acting on the backside of the piston. A passage 36 which is
appropriately tapped with threads is formed in the wall of the
housing 12. This enables pressurized fluid to be introduced. The
piston thus is made double acting by selectively introducing
pressurized fluid on both faces thereof. It will be appreciated
that the surface area of the shoulder 34 is less than the exposed
space in the chamber 24 and accordingly a higher pressure is
required to pressurize the piston from the left.
The piston extends into an axial passage 38 of reduced diameter.
Several O-rings 40 serve as seals preventing leakage. To the left
of the seals 40, the piston is exposed to the mud flow. To the
right of the seals 40, it is exposed to the fluid introduced under
pressure. This is the fluid for actuating the choke as will be
described.
The numeral 42 identifies a laterally extending passage which is a
port for the introduction of mud at high pressure. It is the inlet
port for the choke 10. The opening 42 is encircled by a groove 44.
The groove 44 receives a seal ring. The seal ring is clamped
against a fitting which is connected to the passage. The fitting
itself is preferably equipped with a flange which has a number of
bolt holes drilled in it which match the location of the tapped
openings 46. These enable the flange to be bolted to the body 12,
the body being provided with a flat face in the vicinity of the
port 42.
The numeral 48 identifies a sleeve which is affixed to a central
plug on one end of the piston 26. The sleeve 48 is the valve
element for closure of the choke. It will be observed that the
sleeve 48 is symmetrically constructed at the right and left hand
ends. It is hollow to fit over the circular appendage affixed to
the piston 26. The sleeve 48 is preferably formed of a hardened
metal such as tungsten carbide particles embedded in a base
material. It is made wear resistant. It is equipped with a tapered
leading edge 110. It is axially hollow. This enables it to be
reversed on installation. It is for this reason that the right and
left hand ends are identical.
The sleeve 48 is fastened in place by a bolt 50. The bolt 50
threads axially into a tapped opening formed in the piston 26 for
that purpose. The bolt itself seats into a cup shaped washer 52.
The washer 52 has an encircling shoulder which clamps the sleeve 48
in place. It will be noted that the sleeve 48, at each end, is
undercut with a shoulder which enables the shoulder to receive the
washer 52 to lock the sleeve in place. Further, the sleeve 48 is
jammed against a transverse shoulder 54 at the exposed face of the
piston. This limits its travel. As a consequence, the components
are assembled and held in position for operation in the manner to
be described.
The sleeve 48 serves as a valve element. It is positioned against a
valve seat which is a removable insert indicated by the numeral 56.
The valve seat 56 is a hollow sleeve. It is symmetrically shaped at
the right and left hand ends. At the left hand end, it abuts a
shoulder 58. At the right hand end, a snap ring 60 is used to lock
it into position. The snap ring 60 is received in a groove. The
snap ring locks the sleeve against the shoulder 58. The sleeve 56
is formed of hardened material including tungsten carbide. The
tungsten carbide material is embedded as small particles in a
supporting base metal which is itself a hard alloy. The sleeve 56
fits snuggly in an axial passage extending from the enlarged
chamber communicated with the port 42. The sleeve is provided with
tapered faces 62 at each end. The tapered face serves as a valve
seat which operates in conjunction with a shoulder 64 to receive
and seal on movement of the tapered plug 48 against the seat. The
precise manner of sealing is described later. The sealing action is
self cleaning as will be described. This chokes off flow through
the assembly 10. In the illustrated position, the valve element 48
is spaced from the valve seat.
The sleeve 56 is reversable. The sleeve is easily reversed by
removing the snap ring 60 and sliding the sleeve out, reversing it,
and restoring it to the seated position shown in the drawing. As
will be understood, the bulk of the wear occurs at the upstream end
and very little wear occurs at the downstream end. It is for this
reason that the sleeve can be reversed periodically to enable the
device to have extended life.
The sleeve 56 locks against a downstream shoulder 58 as described.
This limits its travel and specifies its location. This enables the
sleeve to remain stationary as the piston 26 telescopes into the
area adjacent to the sleeve bringing the valve element 48 towards a
sealing or choking position. It will be understood that the valve
element 48 is not always closed against the valve seat 56, but
rather it is moved to a spaced location constricting flow. When the
flow is constricted, the flow is choked by the valve in a manner
determined by the operator.
The left hand end of the body 12 is axially drilled with a passage
and an internal groove is formed for receiving a snap ring 68. The
snap ring 68 holds in position an internal sleeve 70. The sleeve 70
is the downstream outlet sleeve of the apparatus. The body device
terminates at a face 72 which is grooved at 74 to receive a seal
ring. A surrounding flange 76 enables it to be connected with a
mating flange constructed according to industry standards and
suitable holes are provided on a bolt circle to enable the body 12
to be joined to the connective apparatus.
The sleeve 70 is made of a hardened material but it does not have
to be as hard as the material used in the sleeve 56. It is also
made thinner. At this point in the choke, the flow of mud is
basically axial. Therefore, the sleeve 70 is not exposed to the
brunt of the abrasive action which normally occurs in the valve
apparatus.
In operation, the device is connected in a mud line by affixing the
inlet line to the port 42 and an outlet line is connected to the
flange 76 at the left hand end of the equipment. Additionally,
fluid control lines are connected to the threaded and tapped
openings 22 and 36. A convenient technique is to connect a pressure
accumulator topped with a gas (sometimes over a liquid) to the
tapped opening 36. When a suitable hydraulic pressure is introduced
through the opening 22, the piston is forced to the left. When that
pressure is reduced, the accumulator controls the pressure on the
piston to force the piston to the end of its movement. Moreover,
this a fail safe apparatus; should the fluid pressure at the
fitting 22 be lost for any reason whatsoever, the piston slams wide
open.
The valve element and the valve seat jointly have facing tapered
edges. As they close to a gap which might pinch or clamp on a sand
particle, the seat and valve element open to a wider gap
downstream. Thus, any throttling which occurs is between a pair of
concentric tapered surfaces which are aptly suited for long wear.
The wear which does occur is limited because the choked flow is in
fact almost parallel to the tapered faces.
Full closure is achieved at the facing perpendicular seats. They
are fairly well protected from the flow by the position of the
valve and seat in the choke position. As the valve is closed toward
the seat, the tapered opposing surfaces 62 and 110 come toward one
another. They close flow and if sand particles can get into the gap
during closure, the wider gap between facing perpendicular faces 64
and 112 will flush and wash away the debris. Large particles are
blocked upstream of the tapered faces and do not enter the seat
area.The valve element thus chokes upstream of the seating
surfaces. Full closure is obtained on flat facial contact, free of
sand particles and the like. The valve element thus does not close
fully and does not fully constrict on its outer cylindrical surface
until the mud-borne particles are flushed out of the space between
the facing perpendicular shoulders 64 and 112. As will be noted,
the sleeve 48 enters fully within the seat 56 to seat. This
requires that the tapered end portion of the valve telescope into
the seat for closure. The valve has maximum diameter sliding into
the seat itself.
Mud flow is introduced through the passage 42. It impinges directly
on the sleeve 48. The mud is highly abrasive and tends to wear the
sleeve but the wear is resisted by the use of an extremely hard
material in the sleeve. The mud flow of course is diverted to the
left and out through the axial passage. The flow of mud is through
the controlled gap between the sleeve 48 which serves as a valve
element and the sleeve 56 which serves as a valve seat. The
position of the element 48 is thus controlled by the movement of
the piston to regulate or choke the flow. As the flow is choked,
the apparatus 10 serves its intended purpose. More importantly, it
has extended life. That is to say, it is able to choke the mud flow
while tolerating a certain amount of wear but at the same instant,
the wear rate is materially reduced. The wear is basically
localized in the sleeve 48 and the sleeve 56. The two sleeves are
for this reason made of hard materials and are replacable. When the
two sleeves wear out, the apparatus can be disassembled quickly and
easily and the sleeves reversed. They are provided with duplicate
ends. The worn end is switched away from the point of wear, the
point of wear being the facing surfaces for the valve element and
the valve seat.
The foregoing is directed to the preferred embodiment but the scope
of the present invention is determined by the claims which
follow.
* * * * *